1. Field of the Invention
The present invention generally relates to an optical module and an optical connector having the same. More specifically, the invention relates to an optical module for high-speed and large-capacity optical communication using an optical fiber, and an optical connector having the same.
2. Description of the Background Art
In recent years, the request for optical fiber communication technology using optical fibers increases as the speed and capacity for data communication increase. A typical optical module for such optical fiber communication comprises: a photoelectric transfer element package (e.g., a package housing therein a semiconductor light emitting element, such as a semiconductor laser, or a semiconductor light receiving element, such as a photodiode); a ferrule for holding an end face of an optical fiber; a lens; and a holder for housing therein them.
In such an optical module, a photoelectric transfer element in the photoelectric transfer element package is optically coupled with the optical fiber, which is held by the ferrule, via the lens to enable optical communication.
As examples of such optical modules, there are optical modules disclosed in Japanese Patent Laid-Open Nos. 10-300994 and 2002-43675. In these optical modules, a photoelectric transfer element package, a ferrule and a lens are separated, so that an aligning operation for aligning the optical axes of the respective parts with each other must be carried out when the parts are housed in a holder. Therefore, in these optical modules, working and assembling efficiencies are not good.
Therefore, the inventor has diligently studied and proposed an optical module wherein a lens and a holder are formed of a plastic so as to be integrated with each other (Japanese Patent Application No. 2003-026656). In such an optical module, since it is not required to align the optical axis of the lens with the axis of the holder, it is possible to facilitate the assembly of the optical module, so that it is possible to improve the production efficiency of the optical module.
Recently, as a new form of an optical module, there is a tendency to provide an optical module having a light-quantity damping filter for damping the quantity of light traveling between a photoelectric transfer element package and an optical fiber.
For example, such a light-quantity damping filter is arranged between a photoelectric transfer element package and a lens in a holder, in order to prevent excessively strong light from being incident on a semiconductor light receiving element to cause communication errors while causing light to be emitted from a region in which voltage/current characteristics are stable on the side of a semiconductor light emitting element.
However, since the light-quantity damping filter is separated from the holder and lens in the conventional optical module with the light-quantity damping filter, assembling efficiency is not good, and the number of parts is large.
Thus, there is a problem in that an optical module having a light-quantity damping filter can not be inexpensively produced, and effective means for solving this problem have not yet been proposed.